To start things off, you should know that all Milwaukee M18 batteries are designed to work with any Milwaukee M18 tool. There are some physical compatibility issues with a couple of earlier tools, but in those cases, Milwaukee will update those products for free.

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Milwaukee M18 Battery Sizes

There are 3 main M18 battery size categories: CP, XC, and HD.

CP battery packs are the compact batteries, with 5 Li-ion cells. The CP labeling is fairly new, and should help to make things clearer.

HD battery packs are High Demand batteries, built with 15 Li-ion cells. These batteries deliver the longest runtime, and run cooler, keeping up with the heaviest duty Milwaukee M18 cordless power tools.

Milwaukee M18 High Output

Milwaukee announced new M18 High Output batteries in 2018, and has expanded the selection with the addition of a new High Output compact battery, and a higher capacity XC battery.

The “standard” batteries are built with 18650 cells, whereas the new High Output batteries are built with larger 21700 cells. The 21700 Li-ion battery cells are available at higher charge capacities, delivering longer runtime. Not only that, the cells can provided more power, and Milwaukee’s High Output battery packs run cooler.

Thus, the M18 High Output batteries can literally deliver higher output than the “standard” batteries.

An overly simplified way of thinking about it is that a Milwaukee High Output battery bumps you up to the next level of runtime, but in a smaller size battery pack.

The new CP3.0 battery provides higher capacity than the existing CP2.0 battery, and is said to have “XC power” but in a more compact size. The newest XC8.0 battery provides nearly the same charge capacity as the HD9.0 battery.

What do the Numbers Mean?

The numbers following the size designation is the charge capacity. A CP3.0 battery has a 3.0Ah charge capacity; an XC5.0 battery has a 5.0Ah charge capacity; an HD12.0 battery has a 12.0Ah charge capacity.

An Ah is an amp-hour, and can tell you how much runtime a battery will provide, relative to battery packs of other sizes.

Which to Choose?

Generally, you could or should choose the size of battery that is appropriate for the tool. If you’re not sure, check out the contents of that tool’s kit options, if available. A compact drill or impact driver might be best matched up with a compact battery, while a circular saw will likely be better paired with an XC or even HD battery.

Larger battery packs, in an XC or HD battery compared to a CP battery sense, are capable of delivering more power, and run cooler, which can affect runtime and longevity. Of course, they also deliver longer runtime. The High Output batteries cloud things up a little, since they can deliver more power than standard-size batteries of the same CP, XC, or HD size families.

Do you want longer runtime? Select a battery with a higher charge capacity.

Do you want the most for your money? Crunch some numbers and select the battery pack with the lowest price-per-amp-hour ratio, or highest amp-hour-per-dollar ratio. Sometimes the best pricing can be found by buying a 2-pack.

Some users might prefer to buy one XC8.0 battery, while others might instead prefer two XC4.0 batteries. But if you’re running high powered tools, an HD12.0 battery could very well last longer than three XC4.0 batteries.

Also, keep in mind that higher capacity batteries take longer to recharge, and multiple batteries can require greater attention if you have more batteries to charge than you have chargers.

Although the High Output batteries offer higher capacities and can deliver more power than batteries from the same CP/XC/HD class, but they’re also physically larger, and also heavier.

Current Availability

CP3.0 and XC8.0 batteries are coming soon. All the others on the list are presently available.

Compact (CP)

1.5Ah

2.0Ah

3.0Ah – High Output

Extended Capacity (XC)

3.0Ah

4.0Ah

5.0Ah

6.0Ah – High Output

8.0Ah – High Output

High Demand (HD)

9.0Ah

12.0Ah – High Output

Questions?

Hopefully this clears things up. I’d be glad to help if you could use additional clarifications.

Which battery sizes do you typically use? If not with Milwaukee M18 tools, then with your brand of choice?

42 Comments

Excellent explanation, Stuart! Now that the 3Ah is coming out, I’ll have to make another M18 battery performance comparison video. I’ve got something to link people now to instead of typing out a comprehensive explanation myself when I inevitably get questions in the comments section.

You won’t want to use your drill or impact with a 12 on it, unless you have it mounted in some drill press like setup. I would recommend looking at the 6.0 xc HO. More power & more runtime still, but half the weight of a 12. I’m swapping all my 5s for 6s as I go along.

I even have the chainsaw, and bought 6ah HO because I wanted to lessen the weight while using. Made more sense to have two 6s, so you can always be charging one, but will have similar run-time. I still have a 12, but stays on a blower for the most part. For myself, 12s are more appropriate for stationary tools, but often those are lights & radios, so the HO is overkill.

I have two 12s and most of the time they’re plugged into my compact radius lights. The 12 ah will get me through a whole day, whereas I would go through a 5ah, swap it out with my 3ah, and then swap it out again with my other 3ah by the end of the day.

Now I have two lights that I can leave running all day and not have to mess with them, really nice.

So I agree with you, the 12ah batteries are perfect to me for stationary tools like the tablesaw, miter saw, lights, etc.

They really need to discontinue some batteries, no need for 10 and growing options. Will they finally start mixing it up more on whats included with kits. The 6.0 was included in the promo fuel packout bundle, but will it become a permanent fixture in some kits. People dont like buying batteries by themselves because its too expensive. Still surprising the M12 CP 3.0 and XC 6.0 have still never been included in a kit.

For M18 Fuel kits should now come with a CP 3.0 and XC HO 6.0, but thats unlikely to happen anytime soon.

As another user noted, this really does help clear up the increasingly murky battery pack waters.

Some months back I went as far as calling Milwaukee trying to better understand the differences between the M12 CP3.0 vs the XC3.0 and the best I could get out of a couple different people was they use different type and number of cells inside and therefore the XC should last twice as the CP – this in spite of my questioning how that big a difference could be achieved given the identical charge Ah ratings.

Your 9/2018 article on the topic was a FAR better answer to that very question and I’d love to see a similar article to this one on the full M12 battery lineup.

Despite the growth of the respective battery lineups, I can’t see a whole lot of reason to buy any packs other than the top pack in each category (excluding promo/free pack obviously).
M12 – CP3.0 & XC6.0
M18 – CP3.0 & XC6.0 & HD12.0

Pricing can be a factor. While an M12 CP3.0 battery might provide the longest runtime, 2x CP1.5 batteries might be more economical. Or maybe the user wants to have more than one tool equipped with a battery at the same time.

If you’re buying a kit, would you rather spend more for a CP3.0 or XC6.0 battery when a less expensive lower capacity battery would work just fine? There are sometimes different kits with different battery bundles, but they can’t do that for all tools.

The holiday season seemed to prove the need for 3.0Ah 10-cell batteries, which were very aggressively priced.

You show that the 3cp, 6xc, 8xc and 12HD batteries are all listed as High Output batteries.

Does that mean the 9HD doesn’t put out as much power as the 3CP/6XC/8XC batteries, just longer runtime?

So then 1.5cp, 2cp, 3xc, 4xc, 5xc and 9HD are all going to have the same power output, just runtime variation?

Talk about confundilation.

It seems like its time to get rid of older batteries from kits because all we need is the new 3ah compact battery, smaller 5xc battery and 6 and 12 high output batteries for their new more demanding tools.

Eventually all battery packs built with 18650 cells will be killed off due to cost and lack of availability throughout the industry. Milwaukee as with every other battery powered tool MFR are moving away from these older batteries to newer more powerful ones.

I have. I’m referring to your suggestion that 18650 cells will be killed off. As far as I know, ALL M12 batteries, including the new ones, use 18650 cells. They physically cannot use bigger cells like 20700 or 21700 without some form of adapter or special battery pack (e.g. where there are no cells inside the handle part of the pack).

At least put an asterisk on that Milwaukee statement….all Milwaukee batteries work with any 18v tool….
…that is being technically correct,but quite deceiving. While a 2 or 5ah will technically work on a HD 18v tool it certainly won’t allow the tool to function properly.
…. marketing bs
….a HD circ.saw,/table saw/ mitre saw does not function correctly with a lower ah battery on it. It’s not just less runtime,the tool doesn’t work correctly and the battery will get hot , actually damaging the battery.
… Milwaukee knows these HD tools were “designed” for the 9ah and especially the 12ah HO batteries….it’s thier way of staying in one 18v line ,but it’s really not true….like Dewalt flexvolt you need a flexvolt HO battery to run the flexvolt HD tool …it’s the same with Milwaukee…you need their HO batteries to run their HD tools ……
….try using only Milwaukee 5ah or lower batteries on the Milwaukee HD tools and when the batteries are not working anymore, please let me know if Milwaukee is going to replace a bunch of them 5ah for free …

I’ve used the table saw with an XC battery just fine, and no it didn’t overheat. Will it perform the same under demanding tasks as when paired with an HD or High Output battery? No. What about a compact battery? That’s definitely pushing it, and isn’t recommended. But if absolutely necessary, you can probably get light work done in a pinch.

It’s not the best idea to use a compact battery with a heavy duty tool, just as it’s not the best idea to use an HD battery on a compact and lightweight tool. But if you wanted or needed to, you could.

The only real incompatibility I’ve found was using a 2Ah CP battery with the Gen 2 FUEL circular saw while ripping lumber. The battery could handle cross cuts ok, but when the saw needed more juice for a rip the poor little battery overheated less than 8 feet in while repeatedly cutting out. The 5Ah XC was able to do several rips, but did get quite warm.

That’s total BS..there are a number of videos ( not to mention we own all the Milwaukee tools) that show the table saw or mitre saw or HD circ saw boggimg down.you can see and hear the motor struggling with a 5ah….I know you and Stu are sponsored by Milwaukee and need to make a living doing this…
…but your not helping anyone by claiming that crap.
Some poor guy is gonna by those tools and think he is just fine with his pile of 5ah Milwaukee batteries…

Want to explain to me how you think am I misrepresenting the performance again? The side by side comparison I ran with each battery shows the power difference, but the saw is still very much usable with a 5Ah. I also mention the 5Ah and 9Ah get hotter faster too.

I’m not sponsored by Milwaukee. They and other manufacturers send me tools to review, but it does not affect my objectivity in any way. I’ve pointed out plenty of problems in reviews, including the saw blade being out of alignment with the shoe on the Gen 2 FUEL circular saw you love to hate.

It depends on what you’re doing. I had no problem making a few cuts in plywood. It ripped and crosscut a 2×4 as well, no problem. A stack of sheets of plywood, or long rips in 2x4s, and I would have charged the High Output battery.

Advertising has nothing to do with this. My comments aren’t bought or paid for. I’m sorry that you’re wrong and that my first-hand experience conflicts with your opinions, or what you want to be true.

Have YOU used the table saw with an XC battery? No. I have, and I’m telling you about MY experience.

Obviously it’ll reach its full potential with a High Output battery. It’s designed for an HD HO battery. But for light cuts, an XC worked just fine for me. Is that the recommended battery? No. And nobody is claiming that it is.

With a high powered LED flashlight, NiMH or Lithium cells are recommended. Sure, you can fit AA batteries, and it’ll work at light output modes, but you’re not going to get max brightness out of them. Or, if you do, they won’t last for long before heating up. This is the same thing. If your HD HO battery is on the charger, and all you have left to do is cut a few pieces of trim, an XC battery can probably handle it.

“Joe Framer” should be labeled “Milwaukee Hater” because he refuses to understand that higher demand products require higher demand batteries, but at least Milwaukee’s batteries are in FACT fully interchangeable unlike DeWalt’s somewhat incompatible FlexVolt solution. I own and have used my M18 table saw with the 12Ah battery it came with and I even inserted a 2.0Ah battery I use for my M18 nailer and it cross cut some trim boards I needed just to confirm it would run, it did the job just fine. I have used a 5Ah battery a few times when I needed it and had zero issues, it’s a true single battery platform whether he believes it or not!

We own and use more milwaukee tools then the entire blog of commentators….I get your just a diy guy with no experience in the real world of construction, but try not to be blind by the Chinese color red in your eyes..
I actually try to help other people buy the right tools ,while you don’t appreciate professional opinions, I get thanked all the time by those who do..

There’s really no need for an explanation because it doesn’t change the fact that there’s no reason for Milwaukee to have 3 different battery categories to power any of their 18v tools. Nobody else’s battery platform requires a detailed explanation for a battery. Why is there a category for numerical amphours? Dewalt doesn’t have a category for their 20v or 60v batteries whether it’s a 1.5ah or a 12ah. It’s a Dewalt battery. Makita doesn’t do it either. You don’t see a Makita 18v rp3ah battery or an 18v hw8ah battery. Don’t give them an excuse to keep on marketing their batteries like this by rationally explaining their confusing lack of simplicity. You should be questioning why can’t they just keep it simple and explaining how their slick shady approach to marketing their batteries sucks. I bet they’re already scheming about having categories for each numerical amphour battery. e. g. Something ridiculously stupid like 4 different categories for a 5 amphour battery. I bet that’s what they’re planning on doing next. Watch. Only Milwaukee. Why??!! This obviously means that the quality of the cells are different between the categories. I bet if you took apart a battery from each category the cells would be different in each one.

With the charge capacity of compact batteries now overlapping the low end of 10-cell batteries, there needs to be a way to differentiate them. IS that 3Ah battery a compact pack or larger pack? 4Ah? What happens when we get to 5Ah cells?

Ok, I read this article 3 times but am still confused. Do all XC batteries have the same outside dimensions? For example, if I placed an XC 3.0 beside an XC 8.0, will both appear to be the same size when viewed from the outside (ie. disregarding weight, number of cells, etc.)?

The size of XC 3, 4, 5 (and 6 that never seemed to come to market) are the same size. Only other batteries that are the same size are the 1.5 & 2ah compacts.

The XC HO 6.0 is decently larger than any of those, so the 8 should be significantly larger. All the new batteries are based on cells that larger, so regardless of ah, the new batteries will always be wider.

I’ve had sales people tell customers a 2ah battery will last 2 hours with the low-level drill it was packaged with. I then asked him, if that was just drilling into air, as just the material you drill will change the run-time? He changed his response to, the run-time can vary. Smh

A LiPo or Li-Ion cell is around 3.3 V output so you need 5 of them for 18 V. Each one has a certain internal resistance and barring physical improvements which generally are modest improvements to get more power out of a single cell, you have to make it physically wider. For instance you can get much more power out of “D” cells than “AAA” cells in alkaline batteries, let alone 6 V lantern batteries. For a given wire you have a certain amount of resistance so if you keep adding cells in series for higher voltages (12, 18, 24…) you get more power (volts x amps) but at some point the electrical resistance of the battery itself becomes a limiting factor. The solution is to parallel them…10 cells, 15 cells, etc., in parallel strings of 5. So we’re treading on the Milwaukee vs. Dewalt strategies here. But ultimately if the cells are fatter (20700 mAH etc.) or just somewhat improved internal structure they have a lower series resistance even though voltage hasn’t changed at all so you get more power. So the new HO cells are using fatter batteries with modestly higher capacities but also improvements in the internal series resistance. This can go on for years but if the tool doesn’t have some kind of internal current limit, it can overheat with high current output batteries. If there’s a current limiter, then “upgrades” are always possible but “downgrades” can result in underpowering newer tools..like running a chain saw on 1.5 Ah XC’s.

18V comes from 3.6V x 5, with cells sometimes being rated as 3.7V on paper.

It’s not about “series resistance,” but internal resistance. Higher internal resistance means higher thermals. Higher thermals limit the current output, runtime, and longevity. Good cooling can keep thermals controlled to a degree. When thermals exceed cooling capabilities, a well-designed battery will shut off. Over-current protection will sometimes be triggered earlier.

You can increase charge capacity, but the higher charge density often means higher thermals and reduced max output current.

Moving to a larger form factor is about lower charge density, greater cooling, and depending on the tech, also lower internal resistance.

AAA or AA vs D can be about maximum output, but is generally more about runtime so that you don’t have to change batteries so quickly.

Adding more batteries in series combines the voltage. It’s like adding more pressure to a water supply. Adding them in parallel allows for greater current flow. It’s analogous to adding more output pipes to the water supply. Moving to larger cells form factor, and each of those pipes is now a little wider, allowing for even greater flow.

So why isn’t the 3.0Ah compact using the 4.0Ah 21700 batteries making a 4.0Ah CP pack? Likely because of the discharge rate. Generally speaking, the lower the storage capacity (Ah) of a battery the greater its discharge rate (amps). Because the 8.0 and 12.0Ah packs have the advantage of two or three paths in parallel these packs have double (or triple) the discharge rating of the cell. The single path CP pack is limited by the discharge rate of the cell.

For any power tool appropriate for a <4lb battery, the 18v parallel system Milwaukee has is probably fine, and within a few percent of the practical energy supply of a series system like FlexVolt. Whether Dewalt has a better XYZ at the moment than Milwaukee's M18 XYZ probably relates more to other design choices than just battery topology. For example, see the M18 chainsaw, which is a heck of a lot more tool than the Flexvolt Dewalt.

That said, I couldn't care less. What makes me happy after having been burned by Dewalt's very short-lived 36v gear (and I'm sure others feel the same about Milwaukee's V-series) is Milwaukee has just refreshed the battery technology that fits all the tools that I already own, meaning I am assured a supply of batteries to make my $$$$ worth of Red gear continue to function for at least the next decade. THAT is the magic of the M18 any battery fits any tool system.